The first atomic bomb exploded here on 6 August 1945, leaving only a single structure standing - the Hiroshima Peace Memorial (Genbaku Dome). It has been preserved in the same state as immediately preceding the bombing, made possible by the efforts of many people, including those of the city of Hiroshima. It is a barren and powerful representation of humankind most destructive force ever created; however it also communicates the hope for world peace and the eventual eradication of all nuclear weapons. --WHMNet paraphrase from the description at WHC Site, where additional information is available.

Hiroshima Peace Memorial, commonly known as the Atomic Bomb Dome or A-Bomb Dome (Japanese: 原爆ドーム Genbaku Dome), is a UNESCO World Heritage Site located in Hiroshima, Japan. It was established as such in 1996. The site is part of the Hiroshima Peace Memorial Park. The building was originally designed by Czech architect Jan Letzel. It was completed in April 1915, and the new building was named the Hiroshima Prefectural Commercial Exhibition (HMI). It was formally opened to the public in August that year. In 1921 the name was changed to the Hiroshima Prefectural Products Exhibition Hall, and again in 1933 to the Hiroshima Prefectural Industrial Promotion Hall. The 6 August 1945 nuclear explosion was almost directly above the building (the hypocenter was 150 meters / 490 feet away), and it was the closest structure to withstand the explosion. The building has been preserved in the same state as immediately after the bombing, and now serves as the reminder of nuclear devastation and as a symbol of hope for world peace and elimination of all nuclear weapons. --Wikipedia. Text is available under the Creative Commons Attribution-ShareAlike License.